HP 12C manual 02-44 05-44 08-44 10-44 12-43

A useful curve for evaluating sales trends, etc., is the Gompertz curve. This is a "growth" curve having a general "S" shape and may be used to describe series of data where the early rate of growth is small, then accelerates for a period of time and then slows again as the time grows long. The sales curve for many products follow this trend during the introductory, growth and maturity phases.

The data points to be fit to a Gompertz curve should be equally spaced along the x (or time) axis and all the data points must be positive. The points are divided serially into 3 groups for data entry.

The following HP 12C program processes the data, fits it to a Gompertz curve and calculates estimated values for future data points. The 3 constants which characterize the curve are available to the user if desired.

KEYSTROKES		DISPLAY
CLEAR	00-
	01-	43	23
3	02-44	40	3
	03-		33
	04-	43	23
2	05-44	40	2
	06-		33
	07-	43	23
1	08-44	40	1
1	09-		1
4	10-44	40	4
4	11-	45	4
00	12-43, 33		00
3	13-	45	3
2	14-	45	2
	15-		30
2	16-	45	2
1	17-	45	1

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